I have a simple 40 user network that has Monday-morning sickness. Every couple of weeks, most often on a Monday morning, all the computers will lose connectivity to the 8-port Linksys router and the 3 servers. When we try to refresh the IP addresses on the workstations we are not able to get a DHCP address.

The only work around is to power cycle EVERY network device: cable modem, 8-port Linksys router, 2 24-port ASUS 10/100 switches, 3 4-port switches (used to expand the network without running additional cable drops), 3 servers and 3 network printers. The only DHCP server on the network that we are aware of is the Linksys router. Re-booting all these machines is very time consuming. 30 to 40 employees at about $20 per hour each. 1/2 hour to reboot all the machines on Monday morning is $300-$400 in lost productivity. Is Monday morning network sickness a common problem? What plan should I follow to find the source of the problem?

We want wireless connectivity on one side of the building so I am planning to add another router for about 12 users. My thinking is that this might segment the network and may narrow down the source of the problem. Is this a good start?
-- GLF

Having problems on a Monday morning with the regularity you describe definitely is not normal. The good news is that this degree of regularity help diagnose the problem.

Based on what you have described, I would initially focus on the Linksys router. For the size network you have, I would definitely recommend having the DHCP service be provided by one of the servers and not the router. It is fine for providing DHCP for a small office or home network but it has limits on being able to serve up some of the advanced DHCP functions you'd want as your network grows.

The default IP address pool on the Linksys routers I have seen is somewhere in the 40 to 50 IP address size. Depending on the revision of the firmware in your router, you might be able to see the number of devices that have currently been assigned an address by the DHCP server in the router. Look at the size of the DHCP address pool and compare this against the listing of the assigned IP addresses. This should tell you quickly if the pool is being exhausted.

If you have experience in using a packet sniffer such as Wireshark or one of the commercially available packages, use it when turning on a workstation when things are running normally and then try it again when the connectivity problem shows up. Look at the two trace files to compare the two states. That should also help you concentrate your efforts on where the problem is.

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